1. Field of the Invention
The present invention relates to a pixel and a organic light emitting display using the pixel, and more particularly to a pixel and a organic light emitting display using the pixel capable of displaying an image of uniform luminance.
2. Description of the Related Technology
Recently, various flat panel displays have been developed, which substitute for a Cathode Ray Tube (CRT) display because the CRT display is relatively heavy and bulky. Flat panel displays include Liquid Crystal Displays (LCDs), Field Emission Displays (FEDs), Plasma Display Panels (PDPs), Organic Light Emitting Displays, etc
An organic light emitting display displays an image using an organic light emitting diode that generates light by the recombination of electrons and holes. Such an organic light emitting display has advantages in that it has a high response speed, and operates with low power consumption.
FIG. 1 is a view showing a conventional organic light emitting display. With reference to FIG. 1, the conventional organic light emitting display includes a pixel portion 30, a scan driver 10, a data driver 20, and a timing controller 50. The pixel portion 30 includes a plurality of pixels coupled with scan lines S1 to Sn and data lines D1 to Dm. The scan driver 10 drives the scan lines S1 to Sn. The data driver 20 drives the data lines D1 to Dm. The timing controller 50 controls the scan driver 10 and the data driver 20.
The timing controller 50 generates a data drive control signal DCS and a scan drive control signal SCS according to externally supplied synchronous signals. The data drive control signal DCS generated by the timing controller 50 is provided to the data driver 20, and the scan drive control signal SCS is provided to the scan driver 10. Furthermore, the timing controller 50 provides externally supplied data Data to the data driver 20.
The scan driver 10 receives the scan drive control signal SCS from the timing controller 50. Upon the receipt of the scan drive control signal SCS, the scan driver generates a scan signal, and sequentially provides the generated scan signal to the scan lines S1 to Sn.
The data driver 20 receives the data drive control signal DCS from the timing controller 50. Upon the receipt of the data drive control signal DCS, the data driver 20 generates a data signal (predetermined voltage), and provides the generated data signal to the data lines D1 to Dm in synchronism with the scan signal.
The pixel portion 30 receives a first power supply ELVDD and a second power supply ELVSS from an exterior source, and provides them to individual pixels 40. Upon the receipt of the first power supply ELVDD and the second power supply ELVSS, the pixels 40 control an amount of current to the second power supply ELVSS from the first power supply ELVDD through an organic light emitting diode corresponding to the data signal, thus generating light corresponding to the data signal.
That is, in the conventional organic light emitting display, each of the pixels 40 generates light of a predetermined luminance corresponding to the data signal applied to that pixel. However, due to non-uniformity of threshold voltages and a deviation of electron mobility of transistors included in each pixel 40, the conventional organic light emitting display can not display an image of a uniform luminance. In order to solve this problem, an electric current can be supplied as a data signal. In practice, when the electric current is supplied as the data signal, even though the transistors have non-uniform voltage-current characteristics, the pixel can display an image of uniform luminance at the pixel portion 30. However, because the current supplied as the data signal is a minute current, it takes a long time to charge a data line. For example, assuming that a load capacitance of the data line is 30 pF, a time of several ms is required to charge the load of the data line with a data signal from several tens nA to several hundreds nA. Upon considering one horizontal period of several tens μs, there is a problem in that the required charge time exceeds the scan time, thus not allowing sufficient time to charge the date line.